Micro-electrical-mechanical systems (MEMS) devices come in a variety of different types and are utilized across a broad range of applications. One type of MEMS device that may be used in applications such as radio frequency (RF) circuitry is a MEMS vibrating device. A MEMS vibrating device generally includes a vibrating body supported by at least one anchor and including a piezoelectric thin-film layer in contact with one or more conductive layers, which are often referred to as electrodes. As an electrical signal is presented to one or more of the electrodes, the piezoelectric properties of the thin-film layer cause the layer to mechanically deform. The mechanical deformation of the thin-film layer in turn causes changes in the electrical characteristics of the thin-film layer, which may be utilized by circuitry connected to the device to perform one or more functions.
Many different configurations for the piezoelectric thin-film layer and the electrodes have been explored, and often result in variations in the vibrating characteristics of MEMS devices. For example, the piezoelectric thin-film layer of a MEMS vibrating device may be periodically poled in order to enhance one or more vibrational modes of the device, as discussed in U.S. Pat. No. 8,035,280 issued to RF Micro Devices of Greensboro, N.C., the contents of which are hereby incorporated by reference in their entirety. Further, the electrodes of a MEMS vibrating device may be provided in the form of an inter-digital transducer on a surface of the piezoelectric thin-film layer in order to enhance one or more vibrational modes of the device, as discussed in U.S. application Ser. No. 14/031,383, now U.S. Pat. No. 9,391,588, assigned to RF Micro Devices of Greensboro, N.C., the contents of which are hereby incorporated by reference in their entirety. While conventional solutions have resulted in improvements to MEMS devices, there is a persistent need for improved MEMS vibrating devices having high-Q, stability, repeatability, and accuracy while maintaining low loss, motional impedance, and a low temperature coefficient of frequency.